1. Field of the Invention
The present invention relates to tracking inventory. In particular, the invention relates in part to tracking selected items in a shopping cart at a store.
2. Description of the Related Art
Within supply chain management, there is considerable interest in supplementing or replacing the current UPC (Universal Product Code) scheme used to uniquely identify and track inventory items. The current UPC scheme employs a barcode symbology that allows each item to be scanned in, typically at checkout, with an optical scanner. Information contained with the barcode is cross-referenced with an electronic database containing price information for the associated item. This approach has largely replaced older methods of manually typing in the price of each item on a cash register. Individually tagging items with UPC barcodes can reduce incidences of lost, stolen, or spoiled goods, improve the efficiency of demand-driven manufacturing and supply, facilitate the profiling of product usage, and improve the customer experience. However, one disadvantage of item tracking using the UPC scheme is that reading a barcode requires an optical line-of-sight to a UPC scanner, and in some cases appropriate orientation of the bar code relative to the scanner. Also, items with barcodes must be scanned one item at a time. Damage to even a relatively minor portion of the bar code can prevent successful detection and interpretation of the bar code.
Various item-tracking solutions using radio frequency identification (RFID) tags have been proposed as a substitute for using bar codes in supply chain management generally, and particularly in supermarket checkout systems. Proposed RFID-based scanning systems in retail environments typically involve an active scanning device that reads a passive RFID tag affixed to each item. RFID scanners are capable of multi-directional reading of RFID tags from a distance, allowing RFID tracking systems to remotely scan for multiple items in the vicinity of the scanner. Efforts to implement conventional RFID-based scanning systems have, therefore, largely been directed to scanning an entire shopping cart full of items at once, in an effort to save time over the traditional checkout process where item bar codes are manually scanned in one at a time. However, difficulties have arisen in obtaining an accurate accounting of shopping cart contents, due primarily to the size and volume of a typical shopping cart. One difficulty is that items near the center of a typically-sized shopping cart are not reliably detectable with an RFID scanner using existing technology. Furthermore, such solutions still occupy substantial amounts of floor space and overhead.
Despite the shortcomings of previously-proposed RFID-based product scanning systems, however, RFID technology remains a useful tool with a great deal of development potential in supply chain management, inventory management, and, in particular, for expediting checkout at supermarkets and other shopping venues. Therefore, an improved RFID-based inventory scanning solution is desired. The solution would preferably avoid the shortcomings of previously attempted RFID-based systems, such as the inability of known systems to reliably scan an entire shopping cart.